Twenty-five subtracted from one-half a number is 10. What is the number?

70

Step-by-step explanation:

The simplest way to find the number is work backwards. If you know the final answer is 10, start with 10 and make the number x. Then set up the original equation.

0.5x-25=10

Then start working backwards (isolate).

0.5x-25=10

+25 + 25

in other words, 10+25=0.5x. (the 25 cancels out because - 25+25=0)

10+25=35, so 35=0.5x.

Now, instead of dividing by 2, multiply by 2 (opposite again).

35=0.5x

/0.5 (aka * 2) / 0.5 (cancels out)

now you are left with 70=x, so the number is 70.