A man ordered 5 times as many boxes of ballpoint pens as boxes of​ felt-tip pens. Ballpoint pens cost ​$ 4.33 per​ box, and​ felt-tip pens cost ​$.3.45 If the​ man's order of pens totaled ​$​75.30, how many boxes of each type of pen did he​ buy?

-8/2y-8=5/y+4-7y+8/y^2-16

we move all terms to the left:

-8/2y-8-(5/y+4-7y+8/y^2-16)=0

we can not solve this equation

answer: cos [   arcsin (3/5) - arccos (1/2) ] =

step-by-step explanation: × = 3/5 = 0.6--> x = 36.87 and x = 180 - 36.87 = 143.13 deg

cos y = 1/2 --> y = +- 60 deg a. cos (x - y) = cos (143.13 - 60) = cos 83,13  

=

0.12

b. cos (36.87 - 60) = cos (-23.23) = 0.92