The manager of a newsagent ordered 70 copies of XYZ magazine?

s of these were charged at 95p each and the remainder, d, were charged at a discounted
price of 85p each. The bill for all 70 copies was £62.00. How many magazines
were charged at the discounted price? Solve using simultaneous equations.

s + d = 70
.95s + .85d = 62

multiply first equation by .95, then sebtract 2nd equation to eliminate s:

.95s + .95d = 66.5
– (.95s + .85d = 62)
—————————–
.10d = 4.5
d = 4.5/0.1
d = 45

s + d = 70
s + 45 = 70
s = 70 – 45
s = 25

25 copies were charged at 95p and 45 copies were charged at 85p