Solve the system of equations using linear combination. -4x+y=10 -2x-y=-1

In djkl, side jk measures 10.6 inches, side kl measures 7 inches, and side jl measures 5 inches. based on the information that is provided, which could be a correct set of angle measures for these sides? angle j = 23.2°, angle k = 33.5°, angle l = 23.2° angle j = 23.2°, angle k = 33.5°, angle l = 123.2° angle j = 123.2°, angle k = 23.2°, angle l = 33.5° angle j = 33.5°, angle k = 23.2°, angle l = 123.2°

There are 15 plates and each plate is either 7 or 12 inches diameter. which systems of equations do you use to find the number of 7 inch plates, x and 12 inch plates, y

How do you solving the solution of each system using elimination?