James bought 32 bolts at the hardware store for a total of $12.00. some were 3-inch bolts that cost 36 cents each and the others were 4-inch bolts that cost 42 cents each. how many 3-inch bolts did james buy?

Given:

32 bolts for a total of $12.00

3-inch bolt costing 36 cents or 0.36

4-inch bolt costing 42 cents or 0.42

let x represent 3-inch bolt costing 36 cents

let y represent 4-inch bolt costing 42 cents

x + y = 32

0.36x + 0.42y = 12

x = 32 - y

0.36 (32-y) + 0.42y = 12

11.52 - 0.36y + 0.42y = 12

-0.36y + 0.42y = 12 - 11.52

0.06y = 0.48

y = 0.48/0.06

y = 8

x = 32 - y

x = 32 - 8

x = 24

James bought 24 pcs of the 3-inch bolt and 8 pcs of the 4-inch bolt.

To check

0.36x + 0.42y = 12

0.36 (24) + 0.42 (8) = 12

8.64 + 3.36 = 12

12 = 12