Question

10% of what number is 78?

Answer 1

0.1 x [number] = 78
[number] = 78/0.1
[number] = 78 / (1/10)
[number] = 78 * (10/1) --> dividing is the same as multipling by the reciprocal.
[number] = 780

78 is 10% of 780.

Answer 2

Answer: x = 780

Step-by-step explanation: Well percent means over 100 so we can set up an equation for this problem by reading it from left to right.

So we know that 10% means 10/100, of means times, what number means x, is means equals, and 12 means 12.

Notice that 10/100 can be reduced to 1/10.

So rewriting our problem we have X/10 = 78.

To get rid of the fraction, we multiply both sides of the equation by 10 and we have x = 780. So, 10% of 780 is 78.

Now let's check our answer back in the original problem to see if it makes sense.

We have 10% of 780 is 78. Well we know that 100% of of 780 would be 780 so 10% of 780 should be alot less than 780 so 78 seems to make sense.

Image provided showing my work.