
Ahmad B. answered 01/08/20
An investment in knowledge pays the best interest," B. Franklin
If we denote by x the number of roses and y the number of tulips and assuming there is nothing other than roses and tulips, then we must have that
x + y = 144
that means that the sum of number of roses and the number of tulips should be the total number of flowers
Also we must have
y/x = 15/9 (or 15x = 9y)
because for every 9 roses we have 15 tulips
We then get two equations in two unknowns
x+y=144 (1)
15x=9y (2)
Expressing the second as y = (15/9)x and replacing it in equation (1) we get
x + (15/9)x = 144
that is
(24/9)x = 144
or
x =(144)/(24/9) = 54
Replacing this value of x in (1) we get 54 + y =144 or y = 144-54 = 90
This means that
x = 54
y = 90
So we have 54 roses and 90 tulips