To answer this question you have to create a system of equations. The first equation will be that Devi's money (x) equals her brother's money (y), or x = y. The next equation would be that (3/5)x + (7/10)y = 78. You than can substitute x in for y because x = y. The equation would know be (3/5)x + (7/10)x = 78. You then combine the like terms to create an equation of (13/10)x = 78. Then, multiply both sides by 10 / 13 in order to isolate x. This will create the equation x = 60. This means that Devi and her brother each had 60 dollars. You then find out how much they spent and add it together. You can do so with the equation (2/5)x + (3/10)y = z, with z being total money spent. You substitute 60 in for x and for y then solve. When you solve you see that 24 + 18 = z, or that z equals 42. In other words, they spent 42 dollars altogether.
If the weight of the little brother is x, then the weight of Charles is x + 9
The equation that can be used to determine what each one weighs is:
x + (x + 9) = 99.
Let us now solve it.
x + x +9 = 99
2x + 9 = 99
2x = 99 - 9
2x = 90
x = 90/2
x = 45
Little brother's weight is 45 kg.
Charles' weight will be 45 + 9 = 54 kg
Adding these two weights will give 99kg
Answer:
Step-by-step explanation:
Batman
First, note that
is always positive (except for x=0), so
must be always negative.
Thus, the only plausible graphs are 1 and 3 since they are below the x-axis.
Now,
and
are only defined for x≥0, because only for these x'es we can take the square root.
Note that the third graph has domain (-infinity, 0], so it is not the right one, while 1 is ok.
Answer: first graph
