Explanation:
you know how functions work ?
the variable (or variables) in the findings expression is a placeholder for actual values.
when we have an actual value, we put that into the place of the variable and then simply calculate.
x = 5
therefore, the functional calculation is
y = 3×5 - 7 = 15 - 7 = 8
keep in mind the priorities of mathematical operations :
1. brackets
2. exponents
3. multiplications and divisions
4. additions and subtractions
therefore, we need to calculate "3×5" before we deal with the "- 7" part.