The quotient of a number x and - 1.5 is expressed as;
x/-1.5
If the expression is equivalent to 21, then;
x/-1.5 = 21
Next is to calculate the value of x;
x/-1.5 = 21
Cross multiply
x = 21 * -1.5
x = -31.5
the equation is x/-1.5 = 21
Hence the solution is x = -31.5