The function is given by the formula y = 5x + 18 determine the value of x at y = 3.

To determine the value of the variable x at y = 3, if the function is given by the formula y = 5x + 18, substitute the value of y into the formula and solve the resulting linear equation for the variable x.

So, if y = 3, then

3 = 5x + 18;

We transfer the terms with x to the left-hand side of the equation, and without a variable to the right-hand side.

– 5x = 18 – 3;

we give similar ones on the right side of the equation.

– 5x = 15;

Divide both sides of the equation by – 5, we get:

x = 15: (- 5);

x = – 3.

Answer: for x = – 3, the function y = 5x + 18 takes on a value equal to 3.