SOLUTION: when 40% of a number is added to 42 the result is the number itself. find the number.

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Question 980388: when 40% of a number is added to 42 the result is the number itself. find the number.
Found 3 solutions by MathLover1, rfer, macston:
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

let's number be x
when 40% or 40%2F100 of a number is added to 42 the result is the number itself, then the number is
%2840%2F100%29x%2B42=x.....solve for x
42=x-%2840%2F100%29x
42=%28100%2F100%29x-%2840%2F100%29x
42=%2860%2F100%29x
42%2F%2860%2F100%29=x
%2842%2A100%29%2F60=x
4200%2F60=x
420%2F6=x
70=x
so, the number is 70

check:
if the number is 70, than %284cross%280%29%2F1cross%280%29cross%280%29%297cross%280%29=4%2A7=28
if 28 added to 42 we have 28%2B42=70 which is a number itself


Answer by rfer(16322) About Me  (Show Source):
You can put this solution on YOUR website!
0.40x+42=x
0.40x-x=-42
-0.60x=-42
x=-42/-0.60
x=70
--------------
0.40*70+42=70
70=70

Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
.
To add 40% and get the number, you must already have 60%.
So the question translates to 42 is 60% of what number?
42/0.60=70 ANSWER: The number is 70.
.
CHECK:
Find 40% of the number:
(0.40)(70)=28
Add 40% to 42
28+42=70
And get the number, 70.