Misc: What does the Latin word ‘clarus’ mean?

Questions

Define the value of X: 10x + 3x = 100 + 69?

Solve it: 3x + 2x?

Solve it: 7y - 2y + 3y?

Solve it: 14a x 3a - 8a ?

The grass on the prairie can be eaten up by 27 cattle in 6 weeks. If there are 23 cattle, the grass can be eaten up in 9 weeks. If there are 21 cattle, how many weeks would it take for the grass to be eaten?