I need help pleaseee​

Scrub a dub toothbrushes are $4.00 each. there is a 10% discount, but there is also a 6% sales tax after the discount is applied. what is the new price after tax? round to the nearest penny

Abacteria population is tripling every hour. by what factor does the population change in 1/2 hour? select all that apply

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'