Question

6p + 1m = $9 4p + 2m = $8

Answer 1

6p+ 1m= $9
⇒ 12p+ 2m= $18 (1)

4p+ 2m= $8 (2)

Take (1) -(2), we have:
(12p -4p)+ (2m -2m)= $18 -$8
⇒ 8p= $10
⇒ p= $10/8
⇒ p= $1.25

6p+ 1m= $9
⇒ 6*($1.25)+ m= $9
⇒ $7.5+ m= $9
⇒ m= $9 -$7.5
⇒ m= $1.50.

Final answer: p= $1.25, m= $1.50~

Answer 2

You can multiply 6p + m = 9 by -2 so you gonna have -12p - 2m = -18 then you can say : -12p - 2m = -18 ⇒ -8p = -10 ⇒ p = 10/8 ⇒ p = 1.25  
                 4p + 2m = 8 
so now you can find the m : 6 * 1.25 + m = 9 ⇒ 7.5 + m = 9 ⇒ m = 9 - 7.5 ⇒ m= 1.5 :)))
i hope this is helpful 
have a nice day