A Karen purchased a prepaid phone card for $20.50. Calls cost 9 cents a minute using this card. The credit, C (in dollars), left on the card after it is used for
x minutes of calls is given by the following.
C=20.50 -0.09x
How much credit is left on the card after Karen uses it for 30 minutes of calls?

.09×30=2,70 20.50-2.70=17.80

answer:  

step-by-step explanation:

here x represents the height of the pole,

and, the height of the shadow of the pole is 12 feet.

also, the angle of elevation from the top of the pole is 40°,

therefore,

by the low of sine,

which is the required equation for finding the value of x,