Answer:
Let's define the variables:
M = mother's age
D = daughter's age.
"a mother is twice as old as her daughter"
This can be written as:
M = 2*D
"5 years from now she will be thrice as old as her daughter"
(M + 5) = 3*D
We want to know how old is the mother five years from now.
First, our equations are:
M = 2*D
(M + 5) = 3*D
First, we need to isolate one of the variables in one of the equations, because for the solution we want the mother's age, we should isolate the daughter's age.
Let's isolate D in the first equation:
M/2 = D
Now we can replace this in the other equation:
Now we can replace this on the other equation:
(M + 5) = 3*(M/2)
M + 5 - (3/2)*M = 0
-(1/2)*M + 5 = 0
5 = (1/2)*M
2*5 = M = 10
So the mother is 10 years old (this hasn't a lot of sense, maybe there is a wrong number on the question)
and 5 years from now, the mother will be:
10 + 5 = 15 years old.
Answer:
20 is the longer piece, and 9 is the shorter piece
Step-by-step explanation:
9*2=18
18+2=20
20+9
Answer:
The plant grows 1 cm every day is the incorrect statement
Step-by-step explanation:
The graph shows that for every 10 days the plant grows 1 cm
10/2 = 5
so in 5 days the plant would grow half of what it does in 10 days so 1/2 or 0.5 cm
10/10 = 1
so in 1 day the plant would grow a tenth of what it does in 10 days so 1/10 or 0.1 cm
Answer:
The solution is (-5, -2).
Step-by-step explanation:
We'll use "elimination by addition and subtraction."
Multiply the second row by -2. Our system
– 7x – 10y = 45
-3x - 5y = 25
becomes:
– 7x – 10y = 45
+6x + 10 y = -50
-------------------------
-x = 5, so that x = -5.
Substituting -5 for x in the second equation results in
-3(-5) - 5y = 25, or 15 - 5y = 25. This reduces to
-5y = 10, so that y must be -2.
The solution is (-5, -2).
