Question

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Joanne earned $57 in tips yesterday. Her earnings were $13 less than 7/8 of Erin's earnings.

1. Write an equation to represent Erin's earnings, x.

2. How much did Erin earn in tips?

Answer 1

Explanation:

57 = ⅞x - 13

x= 70(8/7) = $80

Answer 2

9514 1404 393

Answer:

1. 57 = (7/8)x -13
2. $80

Explanation:

1. I find it convenient to use variable names that remind me what they stand for. Here, we can use "j" to represent Joanne's earnings, and "e" to represent Erin's earnings.

j = 57 . . . . . Joanne earned $57

j = (7/8)e -13 . . . . . Joanne's earnings were $13 less than 7/8 of Erin's

Substituting for j, we get one equation for Erin's earnings

57 = (7/8)e -13

Using 'x' for Erin's earnings, this is ...

57 = (7/8)x -13

__

2. We can solve the equation as follows:

70 = 7/8x . . . . . . add 13

80 = x . . . . . . . . . multiply by 8/7

Erin earned $80 in tips.