Jacob spent $400 on books. Math books cost $60 and science books cost $50. If he bought a total of 7 books then how many of each kind did he buy?

5 math books and 2 science books.

Step-by-step explanation:

Let's write a system of equations for this. m= math books and s= science books.

The first equation will be about the price.

60m+50s=400

The second will be about the amount he bought.

m+s=7

Let's solve by substitution.

m+s=7 can be rewritten as s=7-m.

Substitute s with 7-m.

60m+50(7-m)=400

60m+350-50m=400

10m+350=400

10m=50

m=5

Then we can plug it into the first equation.

5+s=7

s=2