  For family $x'=(a_0+a_1\cos t+a_2 \sin t)|x|+b_0+b_1 \cos t+b_2 \sin t$, we
solve three basic problems related with its dynamics. First, we characterize
when it has a center (Poincar\'e center focus problem). Second, we show that
each equation has a finite number of limit cycles (finiteness problem), and
finally we give a uniform upper bound for the number of limit cycles (Hilbert's
16th problem).
