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Work Shown:
x = amount of sales
0.05x = five percent of sales to represent commission earned
21,000+0.05x = add on the base salary to get total salary
21,000+0.05x = 70,000
0.05x = 70,000-21,000
0.05x = 49,000
x = (49,000)/(0.05)
x = 980,000
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Check:
If the real estate agent sold $980,000 worth of property, then s/he earned 5% of 980,000 = 0.05*980,000 = 49,000 dollars in commission.
The total salary for the year is 21,000+49,000 = 70,000 dollars. The answer is confirmed.