Mari spent 81.18 on a pair of jeans and a top. if the top cost 80% of the cost of the jeans, how much did the pair of jeans cost? ( show an algebraic solution)

The cost of pair of jeans is $ 58

Solution:

Let "x" be the cost of 1 jean

Then, cost of pair of jeans = 2x

Let "y" be the cost of a top

Mari spent 81.18 on a pair of jeans and a top

Therefore,

2x + y = 81.18 ------ eqn 1

The top cost 80% of the cost of the jeans

cost of top = 80 % of cost of jeans

y = 80 % of x

y = 0.8x ---------- eqn 2

Substitute eqn 2 in eqn 1

Thus cost of pair of jeans = 2x = 2(29) = 58

Thus cost of pair of jeans is $ 58