Translate the phrase into a mathematical equation.
"The sun of 42 and a number..." this phrase denotes that addition is being done on two numbers, 42 and a number. "a number" can be translated into a variable.
"... is equal to 51" so the whole expression equals 51
Now we have our equation: 42 + x = 51
Solve for x.
42 + x = 51
x = 9
So, x is equal to 9.
