3/2 + 21 = 22.5 or 45/2, but why? what are the steps to get that answer?

Television sizes are based on the length of the diagonal of the television's rectangular screen. so, for example, a 70-inch television is a television having a diagonal screen length of 70 inches. if a 70 inch television's diagonal forms a 29°angle with the base of the screen, what is the vertical height (1) of the screen to the nearest inch? 70 inhin

The points (1, 7) and (0, 2) fall on a particular line. what is its equation in slope-intercept form?

To start to solve the system of equations below, which number would you multiply in the equation -2x-5y=-1? the two equations are -2x-5y=-1 and 4x+2y=8