If 9x+2y2−3z2=132 and 9y−2y2+3z2=867, then x+y =
(a) 105 (b) 110 (c) 111 (d) 120 (e) 129
pls big yellow

If eh = hg and hg=16, find the diameter of k

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?

Math i have no idea how to do a and b