Please get a tutor instead of going on brainly.com, and using the space needed for other people who have a legitimate question to have an answer. Other than that, what are you struggling with?
Sinα=h/L
α=arcsin(h/L)° we are told that h=18 and L=20 so
α=arcsin(9/10)°
α≈64° (to nearest whole degree)
X= # of multiple choice questions
y= # of word problem questions
EQUATION 1:
x + y= 25
EQUATION 2:
3x + 4y= 90
STEP 1:
solve for one variable in equation 1
x + y= 25
subtract y from both sides
x= 25 - y
STEP 2:
substitute x=25-y in equation 2
3x + 4y= 90
3(25-y) + 4y= 90
75 - 3y + 4y= 90
75 + y= 90
subtract 75 from both sides
y= 15 word problems
STEP 3:
substitute y value to find x
x + y= 25
x + 15= 25
x= 10 multiple choice questions
ANSWER: There are 15 word problems and 10 multiple choice questions.
Hope this helps! :)