first step is to subtract 21 from both sides
2m+21-21=3-21
2m=-18
2m/2 and -18/2
m=-9
So the final answer is m=-9 (negative nine equals m)
It depends on what variable you are tying to solve for first. Say you are trying to solve for x first and then y on the first problem you wrote.
In substitution you solve one of the equations for example with
6x+2y=-10
2x+2y=-10
you solve 2x+2y=-10 for x
2x+2y=-10
-2y = -2y (what you do to one side of the = you do to the other)
2x=-10-2y (to get the variable by its self you divide the # and the variable)
/2=/2 (-10/2=-5 and -2y/2= -y or -1y, they are the same either way)
x=-5-y
now you put that in your original equation that you didn't solve for:
6(-5-y)+2y=-10 solve for that
-30-6y+2y=-10 combine like terms
-30-4y=-10 get the y alone and to do this you first get the -30 away from it
+30=+30
-4y=20 divide the -4 from each side
/-4=/-4 (20/-4=-5)
y=-5
now the equation you previously solved for x can be solved for y.
x=-5-y
x=-5-(-5) a minus parenthesis negative -(- gives you a positive
-5+5=0
x=0
and now we have solved the problem. x=0 and y=-5
y = 8 -2x
x + 2 (8 - 2x) = 1
x + 16 - 4x = 1
x - 4x = -15
-3x = -15
x = 5
If x = 5, then we can substitute in...
5 + 2y = 1
2y = -4
y = -2
Now let us check that by substituting those values in to the equation
2x + y = 8
2 (5) + (-2) = 8
That is correct so we have the right values for x and y/
Answer:
439.2 miles
Step-by-step explanation:
multiply the days she traveled to the amount of mile she traveled a day
8×59.4 =439.2 miles
Let the distance be x miles
Time = Distance / speed
Time taken by Mike to go to his friend's house = x / 40 hours
Time taken by him to return = x / 45 hours
Total time = x / 40 + x / 45 = 4 hours
= 9x + 8x = 1440 miles
17x = 1440
= x = 1440 ÷ 7
= x = 84.706
Time taken to return home = 84.706 /45= 1.882 hours .
Therefore , Mike took 1.882 hours to reach home .
