Combining like terms

4a-2b-4a-12b

How can writing phrases as algebraic expressions you solve problems?

When you flip a biased coin the probability of getting a tail is 0.6. how many times would you expect to get tails if you flip the coin 320 times?

Which has the greater energy, light of wavelength 519 nm or light with a frequency of 5.42 x 10^8 sec^-1?