Solve 2x+10y=-20 and -x+4y=28 by elimination

Antonio made a scale model of a building. the model's scale is 1 inch to 235 feet and its height is 3.5 inches. what is the exact height of the actual building? enter your answer in the box.

Select all of the quadrants that the parabola whose equation is y=√x-4 (principal square root) occupies. i ii iii iv

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.