Question

Ken bought some pencils and rulers from a shop. Each pencil cost $0.70 and each ruler cost $0.40. Ken bought 7 more rulers than pencils but spent $1.10 less on the rulers than on the pencils.
(a) How many pencils did Ken buy?
(b) How much money did Ken spend on the rulers?

Answer 1

(a)
Let the number of pencils bought be x
Ruler=x+7

cost of pencils=0.7x
cost of rulers= 0.4(x+7)=0.4x+2.8

0.4x+2.8=0.7x-1.1
2.8+1.1=0.7x-0.4x
3.9=0.3x
x=13
number of pencils bought= 13

(b)
number of rulers bought=13+7=20
cost=20(0.40)
=$8.00