When solving an equation with two variables, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)
If c = 1 and x = 6, what is the value of 9c(c - x)?
| 18 | |
| -20 | |
| 90 | |
| -45 |