4. One half of A's marbles exceeds one half of B's and C's together by 2; twice B's marbles falls short of A's and C's together by 16; if C had four more marbles, he would have one fourth as many as A and B together. How many has each? (College Entrance Board.)
5. The sides of a triangle are a, b, c. Calculate the radii of the three circles having the vertices as centers, each being tangent externally to the other two. (Harvard.)
6. Solve
graphically; then solve algebraically and compare results. (Use coördinate or squared paper.)
Factor:
7.
8.