Help I have no clue what I am doing

If private savings 'v' = 0.75s and total savings 's' equals $4.20 billion, solve for public and private savings.

Look at the figure below: triangle abc is a right triangle with angle abc equal to 90 degrees. the length of ac is 5 units and the length of ab is 4 units. d is a point above c. triangle adc is a right triangle with angle dac equal to 90 degrees and dc parallel to ab. what is the length, in units, of segment cd?

If t8 = 4 and t12 = −2, find the first three terms of the arithmetic sequence.