What subject is this if this is math I am good at it
Half life means only half of matter is left, which means half is decayed/radiated.
Formula for half life is
t/2 = [(elapsed time)*(log2)]/[log(beginning amount/ending amount)]
1. t/2 = [(10)*(log2)]/[log(100/76.1)] = 25.378 minutes.
t/2 = [10 * 0.301]/[log 1.314] = [3.01]/[0.1186] = 25.378
2. 53.12 = [(T)*(log2)]/[log(15/4)], on solving we get, T = 101.29 days
53.12 = [T * 0.301]/[log 3.75] = [0.301 * T]/[0.574],
T = [53.12 * 0.574]/[0.301] = [30.49]/[0.301] = 101.29<span />
Let, cost of 1 hot dog and 1 drink is x and y respectively.
Carl bought 4 hot dogs and 6 drinks and paid $23.80.
4x + 6y = 23.80 ....1)
Susan purchased 4 hot dogs and 2 drinks and was charged $15.40.
4x + 2y = 15.40 ....2)
Subtracting equation 2 by 1, we get :
(4x + 6y) - (4x + 2y) = 23.80 - 15.40
4y = 8.4
y = $2.1
4x + 6×2.1 = 23.80
4x = 23.80 - 12.2
4x = 11.6
x = 2.9
Therefore, the cost of 1 hot dog and what is the cost of 1 drink is $2.9 and $2.1 respectively.
Hence, this is the required solution.
Answer: choice B, 40.5 degrees
The triangle is isosceles based on the fact that AC = BC (the tick marks are the same). The angles opposite the congruent sides are also congruent
angle A = angle B = x for some unknown number x
The three angles A,B,C add to 180, so,
A+B+C = 180
x+x+99 = 180
2x+99 = 180
2x = 180-99
2x = 81
x = 81/2
x = 40.5
So angle A and angle B are both 40.5 degrees
Check:
A+B+C = 180
40.5+40.5+99 = 180
180 = 180 answer is confirmed
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Edit
The sides with the two tick marks are the same length, so 7x-4 is the same as length as 31
7x-4 = 31
7x = 31+4
7x = 35
x = 35/7
x = 5
Answer is choice B) 5
