Pounds: 10 20 30
Kilos: 4.5 9 13.5
half of 20 is 10, and half of 9 is 4.5. So every 10 pounds is 4.5 kilos. Add 10 to 20 to get 30, and add 4.5 to 9 to get 13.5. Both parts of the ratio table are increasing at the same rate (either 10 eachtime or 4.5 each time).
You multiply 16 by 11 to get k, which is 176!
Let the time he spent bicycling at 11 mph be x and the time spent bicycling at 15 mph be y, then
x + y = 60 . . . (1)
7x + 11.75y = 600 . . . (2)
(2) x 7 => 7x + 7y = 420 . . . (3)
(2) - (3) => 4.75y = 180
y = 180 / 4.75 = 38
x = 60 - 38 = 22
Therefore, he should bicycle 22 minutes at 11 mph and 38 minutes at 15 mph.