What is the y-intercept of the equation?

Find the length of the following tangent segments to the circles centered at o and o' whose radii are 5 and 3 respectively and the distance between o and o' is 12. what is the tangent segment of cd?

Dylan and dusty plan to take weekly surfing lessons together. if the 2-hour lessons are $20 per person and they plan to spend $100 each on new surfboards, what is the maximum number of lessons the two can take if the total amount spent for lessons and surfboards is at most $480?

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