pleaseeeeeeeeeeeeeeeee help

Question

Points​ P, Q,​ R, and S are collinear. Point Q is between P and​ R, R is between Q and​ S, and

PQ≅RS.

If

PS=21

and

PR=18​,

what is the value of​ QR?

Answer 1

Points​ P, Q,​ R, and S are collinear. Point Q is between P and​ R, R is between Q and​ S, and

PQ≅RS.

If

PS=21

and

PR=18​,

what is the value of​ QR?

QR is 13 since ps =21 and pr=18 rs=4 and pq =4, so 21-8= 13

Answer 2

Draw a figure.

Let PQ = x. Then RS = x

Let QR = y

Then PQ + QR = PR ⇒ x + y = 18 Equation 1

Also we are given that

PQ + QR + RS = 21 ⇒2x + y = 21 Equation 2

Now solve the system