please show work and solve 1-5. will upvote.

Problem 1 x=-7 y=4 Solve the following simultaneous equations, where and y are unknowns: 21=Sxt 5x+6y=3x +10 110y+2556 Problem 2 Solve the following simultaneous inequalities, and write down the range of 3 as a function of y 10x+3y7y+5 & S7 Eye (6y-55-25-10 X Problem 3 Let M be a function of M(x) = ax +bx+c where a, b, and care constants. What is the first-order derivative of M with respect to , ie AM dr + Problem 4 Let M be a function of : M(x) = ax + bx + c where a, b, and care constants. What is the value of that maximizes the value of M(x)? Problem 5 A and B are two random variables. Both A and B follow normal distributions as follows