The answer is in the image
y=2x+15
where y=Value of coin
x=Age in years
Value of coin after 19 years=2*19+15
=$53
Therefore, Value after 19 years=$53
The wood before starting =12 feet
Left wood=6 feet
Wood used till now=12-6=6 feet
Picture frame built till now= 6/(3/4)
=8 pieces
Therefore, till now 8 pieces have been made.
30% of 420 are first year students
first year students = (30/100 )*420
=126 students
Student who are not in first year = 420-126
=294 students
tip=18% of 75.45
=18/100 * 75.45 = $13.581
Tip = $13.581
Let the father's age be x and son's be y
10 years before-
Father age=x-10
sons age=y-10
Given,
x-10=10(y-10)
x-10=10y-100
Given present age of father=40
therefore,
x=40
40-10=10y-100
10y-100=30
10y=130
y=130/10
y=13
Therefore present age of son=13years
It will provide an instant answer!