Question 1167930
let p equal the cost of one pencil.
let e equal the cost of one eraser.


your equation is p + e = 15


if the cost of 1 pencil is 5 naira, then:


p + e = 15 becomes 5 + e = 15


start with:
5 + e = 15
subtract 5 from both sides of the equation to get:
e = 15 - 5
combine like terms to get:
e = 10


that's the price of 1 eraser.


when 60 erasers are bought, ....


cost = 60 * 10


solve for cost to get:


cost = 600 naira.