Which boat race?

Today in 1864 was the first time that a special boat race took place which is still run between the same two teams in the present day.

What is it called, where is it run, who won the first time, against who and who won it the last time?

There are two types of musical instruments hidden in the letters missing from the alphabet below, what are they?

M Q V C X K R H B G D J W S Z Y

56, divide by 8, x 12, 75% of this, – 46, triple it =

13, x 6, x 3, -42, halve it, 11/12 of this =

126, 13/14 of this, triple it, -79, divide by 17, x by itself =

306, divide by 18, x 11, triple it, -353, 7/16 of this =

Have fun and keep safe.

Mr Hopegood