Daniel builds rocking chairs and tables in his shop. It takes him 4h to build a rocking chair and 7h to build a table. Last week he worked 50h. What equation expresses the number of tables he made in terms of the number of rocking chairs?
A. t = 50 - 4r / 7
B. r = 50 - 7t / 4
C. 50 - 4r = 7t
D. 4r + 7t = 50
Please explain to me how. Thanks.