The earth is composed of multiple layers, which can be defined either by composition or by mechanical properties. this layer is key to plate movement. it is a solid but flows like a very viscous fluid. it is the

63 + is a common factor of 9
9(7 + 4) < == this is equivalent

63 + is a common factor of 3
3(21 + this is not an answer it is equivalent

To calculate this you’ll have to subtract and then divide
1500= 500+50t
1.) subtract 500 from 1500 to break down the equation
1500-500 =500+50t -500
1000= 50t
2.) now you want to get t alone... so since t is multiplied by 50, you will do the opposite and divide 50 from 1000 in order to get rid of it- which will again break down the equation
1000 /50= 50t /50
20= t

The answer is 20 minutes
Hope this helps x