In the following equations a and b are equal. which number could be substituted for both a and b to make both equations correct? a. 15 x 0= -36 + a b. 24 x 8 x 0 = 36 - b a.-36 b.51 c.36 d.-51

 Considering the first equation 15 × 0 = -36 + a 
 15 × 0 = 0
therefore, -36 + a =0
In the second equation
 24 × 8 × 0 = 36 - b
Consider the LS 
24 × 8 × 0 = 0
Therefore, 36 - b = 0
we are left with the two equations,
 36 - b = 0
-36 + a = 0
then, we calculate the number that can be substituted to satisfy the two equations.
solving the equations
 b = 36, and a = 36
Therefore, 36 is the number that can be used to substitute a and b in the equations