The ratio of girls to boys in an after school club is 4:5. If there are 12 girls, how many boys are there?

15 bc ratio 4:5

multiply 4×3 u get 12 same thing to 5

end up with 12:15

hello :)

15 boys

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