Answer: He bought 7 nachos.
Explanation:
Let x= Number of cokes
y = Number of nachos
As per given , we have
x+y=12 (i)
2.50x+3.50y=37 (ii)
Multiply 2.5 on both sides of (i), we get
2.5x+2.5y= 30 (iii)
Subtract (iii) from (ii), we get
y=7 (iv)
Put value of y from (iv) in (i), we get
x+7=12
⇒ x= 12-7
⇒ x=5
Hence, he bought 5 cokes and 7 nachos.