Mr. Wayne sells calculators. He marks up every item with a profit of 25%. Let x be his cost for a calculator. A. Write an expression for the selling price of the calculator. b. Find the selling price for a calculator for which Mr. Wayne paid $25. c. Find out how much Mr. Wayne paid for a calculator that he sells for $86.

Step-by-step explanation:

%profit = selling price - cost price/cost price * 100

If Mr. Wayne marks up every item with a profit of 25% and x be his cost for a calculator, the expression for the selling price can be gotten by substituting the parameters into the formula;

25 = sp-cp/cp * 100

25/100 =  sp-x/x

0.25 = sp-x/x

cross multiply

0.25x = sp-x

add x to both sides

0.25x+x = sp-x+x

1.25x = sp

selling price = 1.25x

Hence an expression for the selling price of the calculator is 1.25x

b) If Mr wayne paid $25, the selling price is derived by substituing x = $25 into the expression in (a)

selling price = 1.25x

selling price = 1.25($25)

selling price = $31.25

c) If the selling price is $86, to get the cost of the calculator, substitute the selling price into the expression in (a)

selling price = 1.25x

$86= 1.25x

x is the cost price of the calculator

divide both sides by 1.25

$86/1.25= 1.25x/1.25

x = $68.8

Hence Wayne paid $68.8 for a calculator that he sells for $86.

what is the model?

step-by-step explanation: