30b + 100u = 900
5b + 25u = 200....multiply by -6
------------------
30b + 100u = 900
-30b - 150u = - 1200 (result of multiplying by -6)
------------------add
-50u = - 300
u = 6 <== upgrated phones sold
30b + 100u = 900
30b + 100(6) = 900
30b + 600 = 900
30b = 900 - 600
30b = 300
b = 10 <== basic phones sold
Yep, this is all correct!
-6/2 = y/4
y = (-6×4)/2
y = -24/2
y = -12
x was multiplied by 2
and y was also multiplied by 2
Answer:
1302
Step-by-step explanation:
10C5 + (5C1×10C4) = 1302
What must be true is the expression will actually be adding 10 + (+ x), because of the two marks you have to make when subtracting by a negative.
The subtraction sign is also the negative sign. So in this case, the expression is also saying -x, which means there is two negative signs.
A double negative is a positive, so in this case the x will be turned to a positive integer.
If this is still too confusing, she can plug in a number to replace x. Let’s try it with -2:
Ex. 10 - (-2)= 12.
The two negative signs turn into one positive sign, AKA an addition sign. So, the above expression can be simplified as 10 + 2, or 12.
