I am revising for my smc exam next week, and having trouble understanding
this question

Am astigmatic prescription requires a vertical power of +4.25 and a horizontal power of +6.75 ...

Write out this rx in each of the following forms ...

A) both sph and cyl
B) toric form -3.50 base curve
C) toric form +8.00 sphere curve

I know is means

+4.25 x 180 / +6.75 x 90

so to work sph and cyl form out

isit what gets me from +4.25 to +6.75 = +2.50

then simply 4.25 x 180 / +2.50 x 90? & 6.75 x 90 / -2.50 x 180
for a ?

Many thanks lee, and revising tips or advice would be great :) x