Subtraction with ReadInt

Question

I'm having some issues with my code, it utilized ReadInt, which then gets put into a variable which I call upon to do some basic math. The point of the program is to ask for 5 numbers, add the first two together, subtract the third, then add the fourth and fifth together, and give you the output. However I keep getting an error somewhere and im not sure where. For instance if I use the numbers 3, 10, 7, 6, 1 the answer should be 13, however my program outputs 14, which leads me to believe that its taking 7+6+1 instead of 3+10-7+6+1

    .data       

start BYTE "Please enter 5 numbers.", 0dh, 0ah,0
val1 DWORD ?
finish BYTE "The result of adding the first two numbers,subtracting the third", 0dh, 0ah, 0
finish2 BYTE " and adding the remaining two is ", 0dh, 0ah,0
msg BYTE 0dh,0ah,0  

.code       
main PROC

mov edx, OFFSET start                   
call WriteString                        
call ReadInt                            
mov val1,eax                            
call ReadInt                            
add eax, val1                           
mov val1, eax                           
call ReadInt                            
sub val1, eax                           
mov val1, eax                           
call ReadInt                            
add eax, val1                           
mov val1, eax                           
call ReadInt                            
add eax, val1                           
mov val1, eax                           
mov eax, val1                           
mov edx, OFFSET finish                  
call WriteString                        
mov edx, OFFSET finish2                
call WriteString                        
mov edx, offset msg                     
call WriteString                        

invoke ExitProcess,0
main endp
end main

Answer 1

call ReadInt                            
sub val1, eax                           
mov val1, eax   <-- this is wrong

Since you're subtracting directly from val1 you shouldn't move eax to val1 afterwards (i.e. the mov instruction should should be removed).

What's happening now is that you calculate 3 + 10 - 7 == 6. But then you overwrite val1 with 7, and then you continue by adding 6 and 1 to give you a total of 14.