If the cost of 10 pens is rupees 144.40, then find the cost of 7 pens

Every weekday, mr. jones bikes from his home to his job. sometimes he rides along two roads, the long route that is shown by the solid lines. other times, he takes the shortcut shown by the dashed line. how many fewer kilometers does mr. jones bike when he takes the shortcut instead of the long route?

The measurement of one angle of a right triangle is 42° what is the measurement of the third angle? (there is no picture)

Idon't get undoing if its pass adding and subtracting so can someone ? x-2 over 5 = 18