Answer:
The mean amount spent = £14.80
The modal product is hoodies.
Step-by-step explanation:
Here
25 T shirts each costing £10 were purchased
Amount spent on T shirts = 25 × 10 = £250
30 key ring of £5 were purchased
Amount spent on key ring = 30 × 5 = £150
40 Hoodies for £25 each
Amount spent on Hoodies = 40 × 25 =£1000
30 CD's for £15 each
Amount spent on CD's = 30 ×15 = £450
Total amount spent = 250 +150 + 1000 + 450 = £1850
Total items purchased = 25 + 30 + 40 + 30 = 125
Mean amount spent = 
The modal product is Hoodies as the maximum number of hoodies were purchased.
Answer:
The differential equation is 
Step-by-step explanation:
Differential equation for the rate of change in radiation level:
Radiation level is R.
Rate of change indicates that the radiation level R varies in function of time t, which mathematically means that we have:

After the reactor is shut down, the radiation from the nitrogen-17 decreases in such a way that the rate of change in the radiation level is directly proportional to the radiation level.
Rate of change is k. Decreases means that k is negative. Proportional to the radiation level of R means that -k multiplies R. So the differential equation is:

-2 is the correct answer.
Answer:
B. 1 and -2
Explanation:
First, add up the equations:
x-x+3y+y=4
4y=4
y=1
Now, plug y into any of the original equations above and solve for x:
-x+1=3
-x=2
x=-2
Therefore, the answer is B. 1 and -2