Answer:
Science problems= 12
Math problems= 27
Explanation:
If
x= math problems for solving
y= science problems for solving
x+y=39
y=x-15
Using substitution method:
x+(x-15)=39
2x-15=39
2x=39+15
x=(39+15)/2
x=27
Having "x" lets find out "y" value.
x+y=39
27+y=39
y=39-27
y=12