A) Gavin’s drinks altogether cost £9.00
1.50+2.50x3
=1.50+7.50
=£9.00
b) Lian gets back £3.50
1.50+2.00+3.00
=6.50
10.00-6.50=£3.50
The summation indicates the sum from n = 1 to n = 3 of the expression 2(n+5).
2 (n+5) = 2n + 10
2n + 10 denotes an Arithmetic Series, with a common difference of two and first term as 12.
For n =1, it equals 12
For n = 2, it equals 14
For n = 3, it equals 16
So the sum from n=1 to n=3 will be 12 + 14 + 16 = 42
Sum of an Arithmetic Series can also be written as:

Using the value of a₁ and d, we can simplify the expression as:

This expression is equivalent to the given expression and will yield the same result.
For n=3, we get the sum as:
S₃ = 3(11+3) = 42
To find the decks area we subtract the pool from the total so we times 4 by 5 to get 20 subtracting that from 90 gives us 70 square yards and we then find the square root and get 8.36660026534076
Answer: about 22 minutes
Explanation: its hard to explain but trust me i checked my work
The Triangle Sum Theorem states that the sum of the angles of a triangle equal 180°.
Therefore,
45° + 62° + k = 180
107° + k = 180
k = 73°
The value of k is 73°