Question

A particular chemistry book costs $6 less than a particular physics book, while two such chemistry books and three such physics books cost a total of $123. Construct two simultaneous equations and solve them using the substitution method.

Answer 1

Explanation:

Let's say the Physics book costs $x

The Chemistry book will cost $x - $6

Two such Chemistry books will cost;

2($x - $6) = $(2x - 12)

Three such Physics books cost $3x

$(2x - 12) + $3x = $123

$5x - $12 = $123

$5x = $111

x = $22
`(1)/(5)`

So the Physics book costs; $22
`(1)/(5)`

and the Chemistry book costs $22
`(1)/(5)` - 6 = $16
`(1)/(5)`