Heather loves roses. In her rose garden, she has half as many pink roses as red, and four times as many red ones as white. There are 36 roses that are either yellow or white. Twenty are yellow. How many roses in Heather's garden are there altogether?

so, what do we know?

r = 2p
r = 4w
y+w = 36
y = 20
so, now we see that
y=20
w=16
r = 64
p = 32
r+p+w+y = 132