Please help me with this

How do you find principle and simple interest

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?

4. (10.03 mc) the equation of line cd is y = −2x − 2. write an equation of a line parallel to line cd in slope-intercept form that contains point (4, 5). (4 points) y = −2x + 13 y = negative 1 over 2 x + 7 y = negative 1 over 2 x + 3 − 2x − 3