<span>(5ab + 2a - 4) - (6ab - 6) = 2a - ab + 2
hope it helps</span>
The half life of a decaying substance is defined as the time at which the substance decreases to one-half of its original value. In this case, given hlf-life of 10 years and an original mass of 50 grams, after 10 years, the isotope mass becomes 50*0.5 or 25 grams. Answer is B.
Answer:

Step-by-step explanation:
Since perimeter,
and we know that P=2(l+w) then 
The length will be 
Now 
Step-by-step explanation:
a.
simply add both equations
x + y = 2
-3x - y = 5
----------------
-2x + 0 = 7
x = -7/2
x + y = 2
-7/2 + y = 2
y = 2 + 7/2 = 4/2 + 7/2 = 11/2
b.
1/2 x + 2y = -13
x - 4y = 8
first multiply the first equating by 2
x + 4y = -26
x - 4y = 8
--------------------
2x + 0 = -18
x = -18/2 = -9
x - 4y = 8
-9 - 4y = 8
-4y = 17
y = -17/4
15x ( 7 - 5y) + 3 ( 5y - x) - ( 4x + 3) (5y - 2) = -95xy + 110x + 6 is your solution hope it helps :)!