A rigid smooth retaining wall of height $7 \mathrm{~m}$ with vertical backface retains saturated clay as backfill. The saturated unit weight and undrained cohesion of the backfill are $17.2 \mathrm{kN} / \mathrm{m}^{3}$ and $20 \mathrm{kPa}$, respectively. The difference in the active lateral forces on the wall (in $\mathrm{kN}$ per meter length of wall, up to two decimal places), before and after the occurrence of tension cracks is
A rigid smooth retaining wall of height $7 \mathrm{~m}$ with vertical backface retains saturated clay as backfill. The saturated unit weight and undrained cohesion of the backfill are $17.2 \mathrm{kN} / \mathrm{m}^{3}$ and $20 \mathrm{kPa}$, respectively. The difference in the active lateral forces on the wall (in $\mathrm{kN}$ per meter length of wall, up to two decimal places), before and after the occurrence of tension cracks is