Answer:
Elizabeth spent 17.5 hours and her sister spent 12.5 hours.
Step-by-step explanation:
Let x be the number of hours that Elizabeth shoveled and y be the number of hours that her sister shoveled.
Number of hours they shoveled = 30
So, x + y = 30 or
y = 30 - x
Jenna charged $12 per sidewalk.
So, her total earnings = 12x
Her sister charged $11 per sidewalk.
So, her total earnings = 11y.
Their total income = $347.50.
So, 12x + 11y = 347.5
Substitute y = 30 - x,
12x + 11(30 - x) = 347.5
12x + 330 - 11x = 347.5
x + 330 = 347.5
x = 347.5 - 330
x = 17.5 and
y = 30 - x = 30 - 17.5 = 12.5.
Hence, Elizabeth spent 17.5 hours and her sister spent 12.5 hours.
