Answer:
m = 11
Step-by-step explanation:
Step 1:
10 + m = 21 Equation
Step 2:
m = 21 - 10 Subtract 10 on both sides
Answer:
m = 11
Hope This Helps :)
So x times y=15
x+y=12
solve
x+y=12
subtract x from both sides
y=12-x
subsitute
xy=15
x(12-x)=15
distribute
12x-x^2=15
subtract (12x-x^2) from both sides
0=x^2-12x+15
use quadratic formula which is
x=

where you have
0=ax^2+bx+c
so
a=1
b=-12
c=15
subsitute
x=

x=

x=

x=

x=6+/-

x=6+

or 6-

or aprox
x=10.5826 or 1.41742
the numbers are 10.5826 and 1.41742
X = 4 AND x = -9
Good luck.