SOLUTION: Last month, Alex spent 40% of his salary on a laptop. He then spent 30% of it on his bills and saved the remaining $1200. What was his salary? Can you please explain how to so

Question 528471: Last month, Alex spent 40% of his salary on a laptop. He then spent 30% of it on his bills and saved the remaining $1200. What was his salary?
Can you please explain how to solve this? Thank you.
Answer by oberobic(2304) (Show Source): You can put this solution on YOUR website!
He spent 70% of his salary and had $1200 left.
Let 'x' be his salary.
100%-70% = 30% left.
30%x = 1200
.3x = 1200
x = 4000
.
Check the math.
.4*4000 = 1600
.3*4000 = 1200
4000 - 1600 -1200 = 1200
Correct.
.
Answer: His salary is $4000.
.
Done.
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