If ten is no more than four times the sum of twice a number and three how do i write and work this for algebra

What is the length of the unknown leg in the right triangle ?

Twice the sum of a number and 4 is equal to three times the difference of the number and 7. find the number.

If the speed of an electromagnetic wave is 100,000 cm/s and its wavelength is 100 cm, what is its frequency? a) 100,000 cycles per second (hz) b) 1 × 10-3 cycles per second (hz) c) 10,000,000 cycles per second (hz) d) 1,000 cycles per second (hz)