Answer:
2
Step-by-step explanation:
We are given the distance QA=1.25 and QA'=2.5.
We make the relation 2.5/1.25=2 is the scale factor!
the marked angles are complementary → B
All 3 triangles are right with one angle = 90°
the sum of the angles in a triangle = 180°
thus the remaining 2 marked angles sum to 90°, thus are complementary
Answer:
x=13,y=0
Step-by-step explanation:
We are given a system of equations

For equation 1,square all terms to reduce it
√x²+√y²=169
x+y=13
Make x the subject as required by the question to use substitution method
x=13-y
Plug x=13-y into eqn 2
3(13-y)+2y=39
39-3y+2y=39
39-y=39
y=39-39=0
Plug y=0 into equation 1
x+0=13
x=0
Answer: 
Step-by-step explanation:
We know that the general form of the exponential decay formula is
, where y is final amount remaining after t time, A is the original amount and r is the rate of decay
Now, the ratio of strontium-90 remaining, p , as a function of years, t , since the nuclear accident. 
Hence, the ratio of remaining since the nuclear accident is 