S = Sally
M = Mother
S = M/5 + 10
20 = M/5 + 10
20 - 10 = M/5
10 = M/5
M = 10 * 5
M = 50
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Her mother is 50 yo
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50 : 5 + 10 = 20
the answer is good
Answer:
Step-by-step explanation:
Given
Required
The cost of units used
First, calculate the number of units used.
Next, multiply the units used by the cost per units,
Since the cost per unit is not given, we assume that it is x.
So, the total cost is:
f'(x) =
i) f(x) = 9 / x
ii) f'(x) =
x = 2.95
<u>Step 1: Convert words into an expression</u>
0.45 plus 9x equals 27
0.45 + 9x = 27
<u>Step 2: Solve for x</u>
0.45 + 9x - 0.45 = 27 - 0.45
9x / 9 = 26.55 / 9
Answer: x = 2.95