Simultaneous equations

problem
Warmsnug double glazing

Age

14 to 16

Challenge level

How have "Warmsnug" arrived at the prices shown on their windows? Which window has been given an incorrect price?
problem
Table height

Age

14 to 16

Challenge level

A table has blocks of wood placed on and next to it. Can you work out how tall it is?
problem
Intersection Sudoku 1

Age

11 to 16

Challenge level

A Sudoku with a twist.
problem
Day of the Triffids

Age

14 to 16

Challenge level

Jasmine buys three different types of plant. How many triffids did she buy?
problem
Walls

Age

16 to 18

Challenge level

Plane 1 contains points A, B and C and plane 2 contains points A and B. Find all the points on plane 2 such that the two planes are perpendicular.
problem
Arithmagons

Age

11 to 16

Challenge level

Can you find the values at the vertices when you know the values on the edges?
problem
Nine, ten and one

Age

11 to 14

Challenge level

Can you find the value of t in these equations?
problem
Double time

Age

16 to 18

Challenge level

Crack this code which depends on taking pairs of letters and using two simultaneous relations and modulus arithmetic to encode the message.
problem
Children at large

Age

11 to 14

Challenge level

There are four children in a family, two girls, Kate and Sally, and two boys, Tom and Ben. How old are the children?
problem
Sweet shop

Age

11 to 14

Challenge level

Five children went into the sweet shop after school. There were choco bars, chews, mini eggs and lollypops, all costing under 50p. Suggest a way in which Nathan could spend all his money.