Question

one fifth of a number plus three times the number is equal to twice the number plus 42 what is the number

Answer 1

The term "a number" is going to be our variable, and we will use x to express that unknown number. The term "of" can also mean multiply, so.....

One fifth of a number = 1/5x

Three times the number = 3x

Twice the number = 2x

Now we add the other components to complete the rest of the equation:
1/5x + 3x = 2x +42
And then simplify the equation which comes down to:
x = 35

Answer 2

Let the number be n.

Then n/5 + 3n = 2n + 42

Mult. all terms by 5 to eliminate the fractional coefficient 1/5:

n + 5n = 210

Then 6n = 210, and n = 210/6 = 35

Check! Does (1/5)(35) + 3(35) = 2(35) + 42?
Does 7 + 105 = 70 + 42?
Does 112 = 112 ? YES

The number is 35.