Hi!
So we have to make a system of equations here.
Let sibling 1 be O and sibling 2 be Y (for older and younger)
So:
O + Y = 64
O = 64 - Y
(Either one works)
The older sibling is 6 years older.
O = Y + 6
Make everything in terms of Y.
64 - Y = Y + 6
Same to both:
58 = 2y
2y = 58
Divide by 2 on both sides:
y = 29
Since the older sibling is 6 years older:
29 + 6 = 35
Y = 29
O = 35
Let me know if you have any questions.
25% OFF is 100%-25%=75%
75% is 0.75 in decimal form
if x is the original price then
0.75x=33
x=33/0.75= £44
C.if the user can only enter functions of the form f(x+k), what are all the values of k that would result in the arrow clearing the castle wall
The lateral surface area of a cylinder is just the long side connecting the bases, whereas the total surface area includes both the lateral surface area and area of the two circular bases.

(Imagine a rectangle with the circumfrence of the base as one side and the height as the other being folded around)

(Plus the area of two circles)
The literal difference between surface areas would be the two bases 2πr² if you need that.