For this case we must evaluate the following expression:
14 + (- 8) ÷ 2 * -3
According to the method of algebraic resolution, called PEMDAS, the divisions and multiplications must be made from left to right, before the addition and subtraction, then:
14 + (- 4) * - 3 =
We eliminate the parenthesis keeping in mind that 

Equal signs are added and the same sign is placed:

Answer:
26
3x(4x - 15) < Given
12x^2 - 45x < Distributive law of property
By the way, you are simplifying not solving. You solve equations and simplify expressions.
Answer:
To find the sum of an infinite geometric series having ratios with an absolute value less than one, use the formula, S=a11−r , where a1 is the first term and r is the common ratio.
Spider-Man 120
Superman 40