This does not quite answer the question

21cms x 28cms

Mixed media on found maths papers

Find these values of t

21cms x 28cms

Mixed media on found maths papers

half x + c = y

40cms x 25cms

Mixed media on found maths papers

Rotation Clockwise 90 Degrees

20cms x 26cms

Mixed media on found maths papers

There is an easier way

21cms x 28cms

Mixed media on found maths papers

z is a function of x and y

21cms x 28cms

Mixed media on found maths papers

x0.69

20cms x 26cms

Mixed media on found maths papers